it sounds like you have it under control. I'm sure you already know this, but please do watch him until he kills the mouse while you're feeding live....
hi - he may or may not make it. the chances are very good that he was was WC (wild-caught) and this means 1. you have no way to know his age; and 2....
sometimes it's not even just a matter of size. for such cute little buggers, day geckos can be bloodthirsty, territorial, and aggressive fighters :)...